diff options
Diffstat (limited to 'arch/s390/mm/fault.c')
| -rw-r--r-- | arch/s390/mm/fault.c | 99 |
1 files changed, 45 insertions, 54 deletions
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c index 6d507462967..3df5b918cfe 100644 --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -100,39 +100,28 @@ void bust_spinlocks(int yes) /* * Returns the address space associated with the fault. - * Returns 0 for kernel space, 1 for user space and - * 2 for code execution in user space with noexec=on. + * Returns 0 for kernel space and 1 for user space. */ -static inline int check_space(struct task_struct *tsk) +static inline int user_space_fault(unsigned long trans_exc_code) { /* - * The lowest two bits of S390_lowcore.trans_exc_code - * indicate which paging table was used. + * The lowest two bits of the translation exception + * identification indicate which paging table was used. */ - int desc = S390_lowcore.trans_exc_code & 3; - - if (desc == 3) /* Home Segment Table Descriptor */ - return switch_amode == 0; - if (desc == 2) /* Secondary Segment Table Descriptor */ - return tsk->thread.mm_segment.ar4; -#ifdef CONFIG_S390_SWITCH_AMODE - if (unlikely(desc == 1)) { /* STD determined via access register */ - /* %a0 always indicates primary space. */ - if (S390_lowcore.exc_access_id != 0) { - save_access_regs(tsk->thread.acrs); - /* - * An alet of 0 indicates primary space. - * An alet of 1 indicates secondary space. - * Any other alet values generate an - * alen-translation exception. - */ - if (tsk->thread.acrs[S390_lowcore.exc_access_id]) - return tsk->thread.mm_segment.ar4; - } - } -#endif - /* Primary Segment Table Descriptor */ - return switch_amode << s390_noexec; + trans_exc_code &= 3; + if (trans_exc_code == 2) + /* Access via secondary space, set_fs setting decides */ + return current->thread.mm_segment.ar4; + if (!switch_amode) + /* User space if the access has been done via home space. */ + return trans_exc_code == 3; + /* + * If the user space is not the home space the kernel runs in home + * space. Access via secondary space has already been covered, + * access via primary space or access register is from user space + * and access via home space is from the kernel. + */ + return trans_exc_code != 3; } /* @@ -162,9 +151,10 @@ static void do_sigsegv(struct pt_regs *regs, unsigned long error_code, } static void do_no_context(struct pt_regs *regs, unsigned long error_code, - unsigned long address) + unsigned long trans_exc_code) { const struct exception_table_entry *fixup; + unsigned long address; /* Are we prepared to handle this kernel fault? */ fixup = search_exception_tables(regs->psw.addr & __FIXUP_MASK); @@ -177,7 +167,8 @@ static void do_no_context(struct pt_regs *regs, unsigned long error_code, * Oops. The kernel tried to access some bad page. We'll have to * terminate things with extreme prejudice. */ - if (check_space(current) == 0) + address = trans_exc_code & __FAIL_ADDR_MASK; + if (user_space_fault(trans_exc_code) == 0) printk(KERN_ALERT "Unable to handle kernel pointer dereference" " at virtual kernel address %p\n", (void *)address); else @@ -188,7 +179,8 @@ static void do_no_context(struct pt_regs *regs, unsigned long error_code, do_exit(SIGKILL); } -static void do_low_address(struct pt_regs *regs, unsigned long error_code) +static void do_low_address(struct pt_regs *regs, unsigned long error_code, + unsigned long trans_exc_code) { /* Low-address protection hit in kernel mode means NULL pointer write access in kernel mode. */ @@ -198,11 +190,11 @@ static void do_low_address(struct pt_regs *regs, unsigned long error_code) do_exit(SIGKILL); } - do_no_context(regs, error_code, 0); + do_no_context(regs, error_code, trans_exc_code); } static void do_sigbus(struct pt_regs *regs, unsigned long error_code, - unsigned long address) + unsigned long trans_exc_code) { struct task_struct *tsk = current; struct mm_struct *mm = tsk->mm; @@ -212,13 +204,13 @@ static void do_sigbus(struct pt_regs *regs, unsigned long error_code, * Send a sigbus, regardless of whether we were in kernel * or user mode. */ - tsk->thread.prot_addr = address; + tsk->thread.prot_addr = trans_exc_code & __FAIL_ADDR_MASK; tsk->thread.trap_no = error_code; force_sig(SIGBUS, tsk); /* Kernel mode? Handle exceptions or die */ if (!(regs->psw.mask & PSW_MASK_PSTATE)) - do_no_context(regs, error_code, address); + do_no_context(regs, error_code, trans_exc_code); } #ifdef CONFIG_S390_EXEC_PROTECT @@ -272,13 +264,13 @@ static int signal_return(struct mm_struct *mm, struct pt_regs *regs, * 3b Region third trans. -> Not present (nullification) */ static inline void -do_exception(struct pt_regs *regs, unsigned long error_code, int write) +do_exception(struct pt_regs *regs, unsigned long error_code, int write, + unsigned long trans_exc_code) { struct task_struct *tsk; struct mm_struct *mm; struct vm_area_struct *vma; unsigned long address; - int space; int si_code; int fault; @@ -288,18 +280,15 @@ do_exception(struct pt_regs *regs, unsigned long error_code, int write) tsk = current; mm = tsk->mm; - /* get the failing address and the affected space */ - address = S390_lowcore.trans_exc_code & __FAIL_ADDR_MASK; - space = check_space(tsk); - /* * Verify that the fault happened in user space, that * we are not in an interrupt and that there is a * user context. */ - if (unlikely(space == 0 || in_atomic() || !mm)) + if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm)) goto no_context; + address = trans_exc_code & __FAIL_ADDR_MASK; /* * When we get here, the fault happened in the current * task's user address space, so we can switch on the @@ -315,7 +304,8 @@ do_exception(struct pt_regs *regs, unsigned long error_code, int write) goto bad_area; #ifdef CONFIG_S390_EXEC_PROTECT - if (unlikely((space == 2) && !(vma->vm_flags & VM_EXEC))) + if (unlikely((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_SECONDARY && + (trans_exc_code & 3) == 0 && !(vma->vm_flags & VM_EXEC))) if (!signal_return(mm, regs, address, error_code)) /* * signal_return() has done an up_read(&mm->mmap_sem) @@ -397,12 +387,14 @@ bad_area: } no_context: - do_no_context(regs, error_code, address); + do_no_context(regs, error_code, trans_exc_code); } void __kprobes do_protection_exception(struct pt_regs *regs, long error_code) { + unsigned long trans_exc_code = S390_lowcore.trans_exc_code; + /* Protection exception is supressing, decrement psw address. */ regs->psw.addr -= (error_code >> 16); /* @@ -410,31 +402,30 @@ void __kprobes do_protection_exception(struct pt_regs *regs, * as a special case because the translation exception code * field is not guaranteed to contain valid data in this case. */ - if (unlikely(!(S390_lowcore.trans_exc_code & 4))) { - do_low_address(regs, error_code); + if (unlikely(!(trans_exc_code & 4))) { + do_low_address(regs, error_code, trans_exc_code); return; } - do_exception(regs, 4, 1); + do_exception(regs, 4, 1, trans_exc_code); } void __kprobes do_dat_exception(struct pt_regs *regs, long error_code) { - do_exception(regs, error_code & 0xff, 0); + do_exception(regs, error_code & 0xff, 0, S390_lowcore.trans_exc_code); } #ifdef CONFIG_64BIT void __kprobes do_asce_exception(struct pt_regs *regs, unsigned long error_code) { + unsigned long trans_exc_code = S390_lowcore.trans_exc_code; struct mm_struct *mm; struct vm_area_struct *vma; unsigned long address; - int space; mm = current->mm; - address = S390_lowcore.trans_exc_code & __FAIL_ADDR_MASK; - space = check_space(current); + address = trans_exc_code & __FAIL_ADDR_MASK; - if (unlikely(space == 0 || in_atomic() || !mm)) + if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm)) goto no_context; local_irq_enable(); @@ -457,7 +448,7 @@ void __kprobes do_asce_exception(struct pt_regs *regs, unsigned long error_code) } no_context: - do_no_context(regs, error_code, address); + do_no_context(regs, error_code, trans_exc_code); } #endif |